Dr. Judit Marsillach and her colleagues recently published a new methodology for measuring the activity of Paraoxonase 1.
A new paper by researchers on the University of Washington Superfund Research Program Project 3 describes in detail an improved protocol for characterizing some of the features of Paraoxonase 1 (PON1) that help it provide protection from exposure to certain contaminants and affect susceptibility to disease. Unlike the previously existing protocol, the one reported does not depend on highly toxic substrates and can be carried out in any lab.
The paraoxonases are a family of enzymes that can protect cells and lipoproteins from oxidative stress and inflammation. They are believed to provide protection from certain toxic exposures and disease development. PON1 is synthesized in the liver and is found in circulation bound to high-density lipoproteins. PON1 in particular is known to help detoxify some compounds from a category of neurotoxins known as organophosphates and has been shown to combat the hardening and narrowing of artery walls (atherosclerosis) through multiple modes of action.
PON1 can be produced by several genetic combinations (it's polymorphic). Many scientists who study PON1 characterize its genotype and design studies to assess the associations of different polymorphic forms of PON1 with disease development. For example, some researchers have shown that a change in amino acid at position 192 is associated with an increased risk of developing disease after exposure to contaminants.
According to Drs. Clement Furlong, Lucio Costa and Judit Marsillach, three investigators on UW SRP Project 3, focusing on the genotype alone is not the right way to study the role of PON1 in susceptibility to exposure or disease. "It doesn't matter what the polymorphism is- what matters is how active PON1 is." said Dr. Marsillach. "Genotype alone doesn't predict the activity of PON1. Lifestyle factors also affect the activity of PON1." When it comes to designing therapeutic interventions this is good news.
If PON1's activity level is so important to the degree of protection it provides, why haven't more researchers focused on it? One barrier has been the highly toxic organophosphate substrates that were required, which posed a risk of accidental exposure for those handling these substrates and required special protocols for disposal. The protocol described doesn't require organophosphate substrates and can therefore be carried out in any lab.
Dr. Marsillach's interest in the paraoxonases dates back to when she was a senior in college. It's what first brought her to UW to work in the lab of Dr. Furlong as a post-doc. She's still excited about PON1 research. "PON1 may be very important in Alzheimer's disease and in other diseases like kidney disease. There's also some evidence that autism is associated with a change in PON1 activity. People haven't looked for it in certain tissues because of its exclusive synthesis in liver, but some of us think that PON1 can be transferred from high-density lipoproteins to cells. Maybe it's there? There are still so many unknowns and so much potential."
The complete manuscript is availble here.